- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Contact Lenses || Cosmetic and Prosthetic Contact Lenses
摘要： In this chapter, coloured contact lenses are differentiated into cosmetic lenses, i.e. tinted contact lenses that simply change the colour of the eyes, and prosthetic lenses, i.e. lenses that change the appearance of an unsightly eye, although the term 'cosmetic lenses' is often used for the latter purpose. The fact that contact lenses can provide benefits other than visual is often overlooked, and their ability to change a patient's appearance should not be trivialised. A practitioner who wishes to provide prosthetic lenses for patients with disfigured eyes should have previous wide experience in fitting prescription lenses and tinted cosmetic lenses. The basic principles are the same, and lenses need to be tailored to each patient.
关键词： prosthetic lenses,contact lenses,cosmetic lenses,eye disfigurement,tinting methods
更新于2025-09-23 15:23:52
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Contact Lenses || Optics and Lens Design
摘要： Some aspects of contact lens design and optics are rarely applied nowadays, as they are less relevant to modern practice, but readers may still need to refer to them. They are available at: https://expertconsult.inkling.com/, whereas the more relevant topics are included here. The appendix, available at: https://expertconsult.inkling.com/, also describes various equations that are used in contact lens work, while the online resources include programs relating to both the optics and to lens design. There are two main aspects to be considered when dealing with the optics of contact lenses: the effects on the wearer of the optical differences from spectacles and the necessity for the practitioner to understand the components which affect the back vertex power (BVP) of the contact-lens/liquid*-lens system. There is some overlap of these two aspects, but for the sake of convenience they are discussed separately in the first two sections of the chapter. In the second section a set of approximate rules is included, the use of which should permit practitioners to make quick and reasonably accurate estimates of changes in power caused by altering certain lens parameters. The Cartesian sign convention2 is used throughout. For further understanding of the basic principles involved, readers are referred to the works of Bennett (1985), Tunnacliffe (1993), Freeman and Hull (2003), Douthwaite (2006) and Rabbetts (2007).
关键词： Lens Design,Astigmatism,Optics,Bifocal Contact Lenses,Power Variations,Contact Lenses,Ocular Refraction,Aberrations,Spectacles
更新于2025-09-23 15:23:52
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The effect of part-time wear of 2-zone concentric bifocal spectacle lenses on refractive error development & eye growth in young chicks
摘要： The purpose of this study is to characterize in young chicks the myopia control effects of part-time wear of two-zone concentric bifocal lenses. Nine-day-old chicks (n = 115) were first made myopic with monocular ?10 Diopter (D) single vision (SV) lenses worn for 3 days. Over the 6 days following myopia induction, either 1) two-zone bifocal lenses (?10 D center/?5 D periphery, BFDC) were worn for 12 (full-time), 10, 8, or 6 h, with ?10 D SV lenses worn for the remainder of the day, or 2) BFDC or BFNC (?5 D center/?10 D periphery) lenses were worn every other day (EOD). Control birds wore ?10 D SV lenses every day. Refractive error (RE) and axial ocular dimensions were monitored every three days with retinoscopy and high frequency A-scan ultrasonography respectively. Mean interocular RE and axial length differences after 3 days of myopia induction ( ± SEM) were ?9.6 ± 0.19 D and 0.26 ± 0.01 mm across the groups. At the end of the following 6-day treatment period, equivalent values were: ?10.66 ± 0.28 D, 0.42 ± 0.02 mm (SV-control); 1) ?4.61 ± 0.29 D, 0.26 ± 0.02 mm (BFDC, 12 h); ?4.82 ± 0.23 D, 0.28 ± 0.02 mm (BFDC, 10 h); ?5.21 ± 0.27 D, 0.24 ± 0.02 mm (BFDC, 8 h); ?6.34 ± 0.34 D, 0.25 ± 0.03 mm (BFDC, 6 h); 2) ?8.29 ± 0.29 D, 0.32 ± 0.03 mm (BFDC, EOD), and ?8.83 ± 0.36 D, 0.33 ± 0.03 mm (BFNC, EOD). Overall, full-time BFDC and part-time BFDC and BFNC lens groups exhibited similar changes and were less myopic than the SV group. The results suggest that bifocal lenses may have myopia control effects even when worn part-time, interleaved with standard (SV) myopic corrections, especially if worn for at least 6 h per day.
关键词： Myopia,Axial length,Chicks,Bifocal lenses,Refractive error
更新于2025-09-23 15:23:52
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[Advances in Imaging and Electron Physics] || superconductors and magnetic electron lenses
摘要： The use of superconductors seems a logical step if one wants to make iron-free magnetic lenses or to reduce the dimensions of conventional lenses since, when decreasing the coil size, the current density is increased. In the 1960s and 1970s, research mainly concentrated on the applicability of superconductors to magnetic electron lenses, and took place on a relatively large scale. This is reviewed in Section 2, after a general introduction into superconductivity in Section 1. Superconducting lenses and microscopes did not become popular due to their inconvenient operation and the lack of interest in high-voltage electron microscopy. High-voltage microscopy has been one of the main reasons for working on strong magnetic lenses and, consequently, on the utilization of superconductors. In 1986, with the discovery of high-temperature superconductivity, discussion on the applicability of superconductors to magnetic electron lenses was reopened. In the past, one of the most serious disadvantages in operating superconducting lenses had been related to the use of liquid helium refrigeration, so high-T c superconductors might be employed to overcome this problem, because their cooling demands are much more relaxed. However, especially during the first years of high-Tc superconductivity, despite their high operating temperatures, the materials themselves seemed extremely unfriendly, as they were brittle, sensitive to water, unstable, and difficult to produce. Fortunately, most of these disadvantages have now disappeared and the discussion concerning their utilization assumes a more fundamental character in the sense that most of the properties of the high-Tc materials are known, though a sound theoretical basis has not yet been defined. The properties of high-T c superconductors are the subject of Section 3. The question whether high-Tc superconductors are more appropriate for applications in particle optics than their classical counterparts was considered to be an interesting research topic. Therefore, this work was started as a feasibility study to the use of high-temperature superconductors in particle optics. Most short-term applications in this field were expected to exploit the high current density of these materials at temperatures above liquid helium, so this work concentrated on magnetic lenses as one of the most straightforward high current density applications. Since conventional iron circuit lenses are already used to their limits, as set by the saturation of the ferromagnetic circuit, significant improvements are to be expected only from iron-free lenses or highly saturated pole piece lenses. Their performance is restricted by the current density allowed in the windings and, further, for the iron-free lens, by the attainable mechanical tolerances, since, in the absence of iron, a lack of axial symmetry in the windings directly results in parasitic aberrations. For making small iron free lenses, high-Tc thin films are potentially interesting candidates, as they possess a high current density and can be patterned very accurately using lithographic techniques. Advantages to be expected from thin film lenses are smaller dimensions and better optical properties. An overview of fabrication techniques for high-Tc thin films is given in Section 4. The first attempt to make a coil in a superconducting thin film, using co-evaporated YBa2Cu3O7?x films, is the subject of Section 5. A thin film has to be patterned with some form of spiral in order to obtain a coil. Therefore, thin film lenses basically do not possess full axial symmetry. The relationship between the geometry of a flat coil and its optical properties is given in Section 6. The geometry of a feasible thin film lens element, along with its corresponding optical properties, is given in Section 7 while the technology used to fabricate this lens element is the subject of Section 8. Finally, based upon the work presented here, Section 9 treats the potential applicability of high-Tc superconductors in instruments that employ particle beams.
关键词： magnetic electron lenses,High-Tc superconductors,thin films,capacitive alignment,lens design,YBa2Cu3O7?x,superconductivity,electron microscopy
更新于2025-09-23 15:23:52
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Monodimensional enlargement of resolved field of view in line scan cameras by a single doubly symmetric mirror
摘要： The geometry of the sensed and thus optically relevant area in the image plane of line scan cameras suggests that improvement of the overall system is possible, by joint design of optics and electronics. By a technique named Linear Fovea (LF) proposed in this paper, the optical contrast along the Line-of-Interest (LOI) in the image plane i.e. the location of the opto-electronic sensor, is optimized at the expense of contrast elsewhere. In the LF method, employing a single doubly symmetric surface, the resolved ?eld of view (RFOV) as the merit function, is maximized, by ?nding appropriate Zernike coe?cients describing that surface. The technique is applied on a proof-of-concept single mirror telescope and both MTF analysis and standard target imaging simulation are performed. Results show that by this technique, the RFOV can be doubled, or alternatively the illumination can be increased 2.5 times keeping RFOV unchanged. Furthermore, a rather uniform response is kept along the LOI.
关键词： Foveated imaging,Aberration compensation,Lens design,Wide ?eld angle lenses,Free form optics,Line scan cameras
更新于2025-09-23 15:23:52
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Towards multifocal displays with dense focal stacks
摘要： We present a virtual reality display that is capable of generating a dense collection of depth/focal planes. This is achieved by driving a focus-tunable lens to sweep a range of focal lengths at a high frequency and, subsequently, tracking the focal length precisely at microsecond time resolutions using an optical module. Precise tracking of the focal length, coupled with a high-speed display, enables our lab prototype to generate 1600 focal planes per second. This enables a novel first-of-its-kind virtual reality multifocal display that is capable of resolving the vergence-accommodation conflict endemic to today’s displays.
关键词： focus-tunable lenses,focus stacks,multifocal displays
更新于2025-09-23 15:23:52
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Relationship of Water Content With Silicon and Fluorine Contents of Silicone-Hydrogel Contact Lens Materials
摘要： Objectives: The relationship between water (W) content and silicon (Si) content of silicone-hydrogel (SiHy) contact lens materials was inspected using identical methodologies, equipment, and operators for materials composing 16 types of commercially available SiHy contact lenses. Fluorine (F) content was included in the analysis for the three materials also containing a fluoropolymer. One type of lens consisted of a bulk SiHy material coated with thin layers of conventional hydrogel. Methods: SiHy materials were obtained in the form of 16 contact lens brands purchased on the open market in a common range of refractive powers from -3 to +6 D in single lots. All test lenses were equilibrated at room temperature in a standard saline recommended in the American National Standards Institute Z80.20-2016 and International Organization for Standardization (ISO) 18369-4:2017 standards. W content was obtained gravimetrically, in %, according to those standards for 16 lenses of each SiHy material. Si content was determined in % using inductively coupled plasma optical emission spectroscopy for four digested lenses of each material. F content was determined in % using an ion-selective electrode for four combusted lenses of each of the three fluorinated SiHy materials. W and Si contents of the bulk SiHy material of the coated lens were estimated by computational exclusion of the hydrogel layers. Results: The linear coefficients of determination (R2, n=16) were 0.7576 (relating mean dry Si content [n=4] to mean W content [n=16]) and 0.8819 (relating mean hydrated Si content [n=4] to mean W content [n=16]). When the 4 SiHy materials that were fluorinated or coated were excluded from the analysis, the R2 values (n=12) were 0.8869 and 0.9263, respectively. When F contents and the coating were added to the assessments, the linear coefficients of determination (R2, n=16) became 0.8948 (relating mean dry [Si+F] content to mean W content) and 0.9397 (relating mean hydrated [Si+F] content to mean W content). Conclusions: There is a fundamental negative linear relationship between Si and W contents for SiHy contact lens materials above 35% W content that is followed when F content and hydrogel coatings are empirically added to the analysis below 35% W content. The relationship was tightest for hydrated (Si+F) content and W content, for which the regression equation had an R2 of 0.9397: (Si+F)= -0.3073 (W)+22.148. The relationship between (Si+F) and W therefore seems to be based on composition rather than structure of available SiHy contact lens materials.
关键词： Water content,Contact lenses,Silicone,Silicon,Hydrogel,Fluorine
更新于2025-09-23 15:23:52
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Use of therapeutic non-refractive contact lenses to improve visual outcome after repair of traumatic corneal wounds
摘要： Background: The purpose of this study was to evaluate the effect of use of contact lenses to improve visual outcome after repair of traumatic corneal wounds. Methods: Two groups of patients (n=30 each) with traumatic full thickness corneal wounds were entered into this study. All cases were caused by sharp objects such as a knife or piece of glass that produced a corneal full thickness wound without any other associated ocular injuries. One group was repaired and received medical treatment (non-contact lens group) and the other group was repaired and a soft contact lens was fitted over the cornea, then medically treated (contact lens group). Each patient was followed up until complete healing, the sutures were removed after about 6 weeks, and the patients were followed up for a further 6 weeks, for a complete follow-up period of 3 months, after which postoperative refraction, manifest refractive spherical equivalent, uncorrected visual acuity, and best-corrected visual acuity were measured and compared between the two groups. Results: After repair and follow-up, uncorrected visual acuity ≥0.3 (decimal system) was achieved in 19 cases (63%) in the contact lens group and in only 14 cases (47%) in the non-contact lens group (P=0.018). Best-corrected visual acuity ≥0.6 was achieved in 26 cases (87%) in the contact lens group and in only 17 cases (57%) in the control group (P=0.012). Conclusion: Soft contact lenses can be used after repair of traumatic corneal wounds to improve visual outcome.
关键词： non-refractive contact lenses,traumatic corneal wounds,visual outcome,repair
更新于2025-09-23 15:22:29
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Preoperative automatic visual behavioural analysis as a tool for intraocular lens choice in cataract surgery
摘要： Purpose: Cataract is the main cause of blindness, affecting 18 million people worldwide, with the highest incidence in the population above 50 years of age. Low visual acuity caused by cataract may have a negative impact on patient quality of life. The current treatment is surgery in order to replace the natural lens with an artificial intraocular lens (IOL), which can be mono- or multifocal. However, due to potential side effects, IOLs must be carefully chosen to ensure higher patient satisfaction. Thus, studies on the visual behavior of these patients may be an important tool to determine the best type of IOL implantation. This study proposed an anamnestic add-on for optimizing the choice of IOL. Methods: We used a camera that automatically takes pictures, documenting the patient’s visual routine in order to obtain additional information about the frequency of distant, intermediate, and near sights. Results: The results indicated an estimated frequency percentage, suggesting that visual analysis of routine photographic records of a patient with cataract may be useful for understanding behavioural gaze and for choosing visual management strategy after cataract surgery, simultaneously stimulating interest for customized IOL manufacturing according to individual needs.
关键词： Sickness impact profile,Cataract/psychology,Cataract extraction,Vision, ocular,Visual acuity,Lenses, intraocular,Quality of life
更新于2025-09-23 15:22:29
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Laser-inscribed contact lens sensors for the detection of analytes in the tear fluid
摘要： Tears exhibit compositional variations as a response to ocular and systemic metabolic conditions, and they can therefore be used for the assessment of physiological health. Here, microfluidic contact lenses were developed as wearable platforms for in situ tear pH, glucose, protein, and nitrite ions sensing. The microfluidic system was inscribed in commercial contact lenses by CO2 laser ablation. The microchannel consisted on a central ring with four branches, and biosensors were embedded within microcavities located at the branches ends. The device was tested with artificial tears and colorimetric readouts were performed using a smartphone-MATLAB algorithm based on the nearest neighbor model. Sensors responded within a time range of 15 seconds, and yielded sensitivities of 12.23 nm/pH unit, 1.4 nm/mmolL-1 of glucose, 0.49 nm/gL-1 of proteins, and 0.03nm/μmolL-1 of nitrites. Contact lens sensing platforms may provide on-eye tears screening with applications in the monitoring of the ocular health both in clinics and at point-of-care settings.
关键词： biomarkers,biosensors,tear fluid,Contact Lenses,point-of-care diagnostics
更新于2025-09-23 15:21:01